Dyeing process



Patented Mar. 6, 1928.

UNITED *STATES v 1,661,606 PATENT OFFICE.

AUGUSTE ESCAICH AND JEAN PAUL WOIBIMS,- OF IABIS, FRANCE.

Drama rnocnss.

No Drawing. bpplication flled November 20, 1928,. Serial No. 675,956.and in Germany November 25, 1922.

This invention relates to a dyeing process applicable to all fibres,leathers, hairs and the like which consists in causing reducing agentsto actin either the hot or. cold state in an acid medium on ferri andferrocyanides and in the presence of traces of catalyzing salts or ofmetallic oxides. By ferro and ferricyanides, we means in thisspecification the double cyanides of iron and of analkali metal, sodiumor potassium.

These substances can furnish various colors. They have, moreover, beenused for a long time, for giving-blue (Raymond,

Prussian, French blue etc.).

It is well known that for obtaining these blues one generally usessomewhat considerable amounts of minerals acids, in a first operation,.and tin salts which are relatively of a high price, in a subsequentoperation.

In the present process use is made of the fact that POtB-SSIUIIIferricyanide, in the presence of various reducing agents will dye anyfibres very easily if the medium is slightly acid and contains traces ofcatalyzing mercury compounds.

The best results are obtained by acid mercury sulphate, known as Denigesreagent consisting of yellow'mercu oxide; 50 gr.,

sulphuric acid 200 c. c., dist ed water 1000 c. c. the amount of mercuryoxide may however be increased.

The reducers suitable for use are numerous and will be enumeratedhereinafter, for instance, ordinary sugar'may be employed as as follows20 ,litres of water +50 0. c. of a solution of sugar, at 10% +40 0. c.of a solution sulphate; is brought to the invert the sugar, and then 4040 c. c. of a solution of 10 potassium ferri cyanide for 100 water isadded; fabrics of any kind immersed at the beginning or at the end inthe bath, will be colored blue. With the .above proportions, the coloris very marked on wool, less intense on silk and cotton, but issuflicient for light shades.

It is thus possible to develop very interesting colors with very reducedquantities of alkali metal ferro or ferricyanides and of mineral acid. a

The composition of the bath remaining otherwise'the same, by doublingthe ferncyanide, that is to say, 80 0. cm. at 10% for 20 litres ofwater; a blue which is deep 58 on wool and very decided 011 silk is obofacid mercury boil in order to The same results are obtained with coldtreatment in about 24 hours. 7

With hot treatment, the first stage of coloring of the fabrics resultsbelow. boilnag-point temperature in greens. If desired, with a view toshading, the operation can be stopped at this point before proceeding tothe blue sta e.

In the absence 0 sugar, the mercury sulphate and the ferricyanide "givea blue of' less depth. 7

The sugar can be replaced by equivalent quantities of glucose.

If, theoretically, in an alkaline medium, the reduction oftwo moleculesof ferricy anide is obtained with a molecule of glucose, in practicepractially equal quantities of these two substances can be used. In acidmedium'the proportions hereinbefore indicated give excellent results.

Ferrocyanide substituted for lferricyanide gives lighter colors. With aview to producing a shade or tint, these two substances can be mixed atthe rate of 1 part of ferricyanide and of 1 to 10 parts of ferrocyanide.With these proportions the addition of ferric chloride or sulphate givesvery fine blues.

Instead of sugar, various reducers can be employed and usedin an amountequal to that of .the ferricyanide or to a smaller amount if theconditions of solubility or of economy are in favour of a decrease.

In a quantity equal to that of the ferrocyanide use can be made ofcommercial formic acid, hydroquinone, resorcin, formaldehyde, dextrine,soluble starch, aniline salts, and tannins; in a smaller quantity onewill use the naphthols (0.50 gr. per liter of bath), I

the pyrocatechin of saponin (0.50 gr..for 1 liter).

The colors are especially good when formic acid, naphthols, hydroquinoneor re- Panama wood may be substituted for the sugar and has theadvantage of drawing,

very uniformly. Further it must -be borne in mind that the saponin seemsto adhere to the fibre like a tannic mordant and under the sameconditions, which allows of dyeing blue after washing the fabric byimmersion in the bath. Hence only two reagents will be required in thebath, the acid mercury sulphate and the ferricyanide, the reducer beingcarried by the saponified fibre.

If the reducer employed is itself a chromogen (tannin, na hthols) and isfixed as a mordant on the fi re, it will be possible to alter the bluetint obtained by passing a. previously tanned blue fibre into a bath ofmolybdate or a blue fibre previously naphtholated into a bath of nitrousacid.

We claim- 1. Method of dyeing any fibres with the aid of a doublecyanide of iron and of an alkali metal, consisting in causing to act onthe fibres a slightly acid bath containing a double cyanide of iron andof an alkali metal, an organic reducing agent and traces of a mercurycompound.

2. Method of dyeing any fibres with the aid of a double cyanide of ironand of an alkali metal, consisting in causing to act on the fibres aslightly acid Fat-h containing a ferricyanide of an alkal metal, aferrocyanide of an alkali metal, an organic reducing agent and traces ofa mercury compound.

In testimony, that we claim the foregoing as our invention, we havesigned our names.

AUGUSTE nsoAIoH. JEAN PAUL WORMS.

